In this paper, we have investigated the quality of benzocyclobutene (BCB) and parylene N (PA-N) films after chemical-mechanical polishing (CMP) by x-ray photoelectron spectroscopy (XPS) and atomic force microscopy. The change of surface chemical structure of both BCB and PA-N films after CMP is mainly dependent on the slurry composition and the quality of as-deposited film. Some slurries do not alter the surface structure for PA-N film, but the surface structure changes for all the slurries investigated for BCB. On the other hand, for both PA-N and BCB we find that the higher the quality of the as-deposited film or postdeposition treated film, the higher the quality of the polished film. The polishing time has little effect on the surface chemistry of high quality PA-N films, but does affect the BCB films. The surface morphology for these two polymers becomes worse after CMP. The root-mean square surface roughness for as-deposited PA-N is 90 Angstrom, but after CMP is larger than 200 Angstrom. The roughness for as-spin-coated and polished BCB film is 5 and 20 Angstrom, respectively. A slurry which is good for BCB polishing is not good for PA-N polishing, and vice versa. We conclude that the nature of the polymer film, including its chemical structure as well as the quality of the as-deposited/postdeposition treated film, plays an important role in polymer CMP.